The ratio of the number of boys to that of girls in a school is 5 : 2. If 87% of the boys and 80% of the girls passed in the annual exams, then find the percentage of students who failed in the annual exams.
Show answer & explanation
Correct answer: C
Explanation
The correct answer is option 3 i.e. 15%
The ratio of boys and girls in school is 5 : 7
Thus, the fraction of boys in school is 5/7 and girls is 2/7.
Since 87% of boys passed, and 80% girls passed, then:-
The percentage of boys failed = 1 - 87%
= 13%
The percentage of girls failed = 1 - 80%
= 20%
Thus, the percentage of students who failed:-
⇒ Percentage of Boys failed + Percentage of girls failed
⇒ (5/7)(13%) + (2/7)(20%)
⇒ 65/700 + 40/700
⇒ 105/700
⇒ 15%